Implementation of High Gas Barrier Laminated Films Based on Cellulose Nanocrystals for Food Flexible Packaging

Ghislain Fotie,Stefano Gazzotti,Marco Aldo Ortenzi,Luciano Piergiovanni

doi:10.3390/app10093201

Ghislain Fotie, Stefano Gazzotti + Show 2 more

Open Access

https://doi.org/10.3390/app10093201

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Journal: Applied sciences	Publication Date: May 4, 2020
Citations: 13	License type: CC BY 4.0

Affiliation: University of Milan

Abstract

In this work, three types of cellulose nanocrystals (CNCs) were used: CNCSO3H extracted from wood pulp by sulfuric acid (H2SO4), CNCCOOH extracted from cotton linters by ammonium persulfate (APS) and CNCCOOR obtained by esterification of the previous two CNCCOOH and CNCSO3H. For a comparative assessment of gas barrier performance, plastic films such as PLA, PET, PE, PP, OPP and OPA were selected, coated with the three types of CNCs and finally laminated with a solvent-based polyurethanic adhesive. First, all dispersed CNCs were characterized by apparent hydrodynamic diameter and Z potential by means of dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques, respectively, followed by the crystallinity index (XRD), thermogravimetric analysis (TGA) and evaluation of Fourier-transform infrared spectroscopy (FTIR), as well as the charges density. The surface chemistry of coated plastics (CNCs-P) was assessed by the Z potential through the electrokinetic technique (streaming potential method) and the optical contact angle (OCA). Lastly, laminated films (P-CNC-P) were evaluated by gas permeability measurements at 23 °C and 50–80% RH. It is worth noting that improvements between 90% and 100% of oxygen barrier were achieved after the lamination. This paper provides insights on the choice of cellulosic nanomaterials for the design and development of advanced and sustainable food packaging materials.

Highlights

Cellulose nanocrystals (CNCs) surface chemistry and shape may be utterly different, depending on the type of the extraction and the raw materials used
Three different cellulose nanocrystals derived species were compared in their properties, aiming for a possible application in the food packaging sector
The main problem to be sorted out was the sensibility of the cellulose nanocrystals to moisture that hampered their incorporation into food packaging

Summary

Introduction

Cellulose nanocrystals (CNCs) surface chemistry and shape may be utterly different, depending on the type of the extraction and the raw materials used. CNCs extraction consists of an acidic or oxidative hydrolysis of cellulosic sources (cotton linters, vegetal by-products, wood pulp, etc.). As reported in many papers, CNCs extracted by hydrochloric acid (HCl) are uncharged [1], while those obtained by sulfuric acid (H2 SO4 ) contain sulfate half ester charges [2,3,4], and those extracted by. 2,2,6,6-Tetramethylpiperidin-1-yloxyl (TEMPO) and ammonium persulfate (APS) contain carboxylic charges on their surface [5,6]. Due to their many positive features, like tiny size and high crystallinity, CNCs may be implemented in food packaging materials, in particular as coatings on plastic films, with a consequent.

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